Credential /(krē̇*dĕn"shal)/

Cre·den·tial

Credential

a.
  1. Giving a title or claim to credit or confidence; accrediting.
    Their credential letters on both sides.
    — Camden.

Credential

n.
  1. That which gives a title to credit or confidence.
  2. Testimonials showing that a person is entitled to credit, or has right to exercise official power, as the letters given by a government to an ambassador or envoy, or a certificate that one is a duly elected delegate.
    The committee of estates excepted against the credentials of the English commissioners.
    — Whitelocke.
    Had they not shown undoubted credentials from the Divine Person who sent them on such a message.